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Abstract:

An extruded oriented thermo-plastic polymeric element for industrial
textiles, and textiles comprising polymeric elements. The polymeric
elements are constructed of a material selected from yarn material, fiber
material and film, and comprise a thermoplastic polymer, and at least one
dry lubricant, selected from molybdenum disulphide, tungsten disulphide,
boron nitride, and a soft metal, the dry lubricant comprising particulate
matter having an average particle size between about 0.05μ and about
100μ, and present in the polymeric element in an amount from between
about 0.1% and about 10% parts by weight, based on a total weight of the
polymeric element. The polymeric elements can be used as yarns in woven
and non woven textiles, and as seaming elements. The polymeric elements
provide increased abrasion resistance in industrial textiles, and reduced
co-efficient of friction.

Claims:

1. An extruded and oriented thermoplastic polymeric element for use in an
industrial textile, wherein the polymeric element is constructed of a
material selected from yarn material, fiber material and film, and
comprises (i) a thermoplastic polymer; and (ii) at least one dry
lubricant, selected from the group consisting of molybdenum disulphide
(MoS2), tungsten disulphide (WS2), boron nitride (BN), and a
soft metal, wherein the dry lubricant comprises particulate matter having
an average particle size in a range of between about 0.05.mu. and about
100.mu. (5.0.times.10.sup.-8 m and about 1.0.times.10.sup.-4 m), and is
present in the polymeric element in an amount from between about 0.1% and
about 10% parts by weight (pbw), based on a total weight of the polymeric
element.

3. A polymeric element according to claim 1, wherein the at least one dry
lubricant is selected from the group consisting of tungsten disulphide
(WS2), boron nitride (BN), and a soft metal, and the thermoplastic
polymer comprises at least one polyamide.

4. A polymeric element according to claim 3, wherein the at least one
polyamide is selected from at least one of PA-6, PA-6/6, PA-6/10,
PA-6/12, PA-11, PA-10, PA-12 and polyphthalamide (PPA).

6. A polymeric element according to claim 1, wherein the dry lubricant
comprises between about 0.5% and about 7% pbw of the total weight of the
polymeric element.

7. A polymeric element according to claim 6, wherein the dry lubricant
comprises between about 1% and about 5% pbw of the total weight of the
polymeric element.

8. A polymeric element according to claim 1, wherein the average particle
size of the particulate matter of the dry lubricant is in a range of
between about 0.1.mu. and 50.mu. (1.0.times.10.sup.-7 m and about
5.0.times.10.sup.-5 m).

9. A polymeric element according to claim 8, wherein the average particle
size of the particulate matter of the dry lubricant is in a range of
between about 0.5.mu. and about 20.mu. (5.0.times.10.sup.-7 m and about
2.0.times.10.sup.-5 m).

10. A polymeric element according to claim 1, wherein the polymeric
element comprises a film comprising at least one layer.

14. A polymeric element according to claim 1, wherein the polymeric
element comprises a material selected from a yarn material and film, and
is a seaming element.

15. An industrial textile comprising at least one extruded and oriented
thermoplastic polymeric element, wherein each of the at least one
polymeric element is constructed according to claim 1.

16.-27. (canceled)

28. An industrial textile according to claim 15, wherein the textile
comprises a woven structure including warp yarns and weft yarns.

29. An industrial textile according to claim 15, wherein the textile
comprises a nonwoven structure including MD and CD yarns.

30. An industrial textile according to claim 15, wherein the textile
comprises a nonwoven structure and the at least one polymeric element
comprises a plurality of interconnected helically coiled yarns.

31. An industrial textile according to claim 15, further comprising a
seaming element.

32. An industrial textile comprising machine direction (MD) and
cross-machine direction (CD) elements, wherein at least 25% of the
elements of a set selected from the MD elements and the CD elements are
extruded and oriented thermoplastic polymeric elements, each polymeric
element comprising: (i) a thermoplastic polymer; and (ii) at least one
dry lubricant, selected from the group consisting of molybdenum
disulphide (MoS2), tungsten disulphide (WS2), boron nitride
(BN) and a soft metal, wherein the dry lubricant comprises particulate
matter having an average particle size in the range of between about
0.05.mu. and about 100.mu. (5.0.times.10.sup.-8 m and about
1.0.times.10.sup.-4 m), and is present in the polymeric element in an
amount from between about 0.1% and about 10% parts by weight (pbw), based
on the total weight of the polymeric element.

35. An industrial textile according to claim 15, constructed and arranged
to be used as at least one of an industrial filtration fabric and a
conveying fabric.

36. (canceled)

37. An industrial textile according to claim 15, constructed and arranged
to be used in a section of a papermaking machine selected from a forming
section, a press section and a dryer section, and the fabric is selected
from a forming fabric, a press fabric, a dryer fabric and a through air
dryer fabric.

38.-41. (canceled)

42. A polymeric element according to claim 1, wherein the thermoplastic
polymer is a polyester having an intrinsic viscosity of at least 0.7,
determined using a mixture selected from a 60:40 pbw mixture of phenol
and (1,1,2,2)-tetrachloroethane and a 50:50 pbw mixture of
trifluoroacetic acid and dichloromethane.

43. An industrial textile according to claim 15, wherein the
thermoplastic polymer is a polyester having an intrinsic viscosity of at
least 0.7, determined using a mixture selected from a 60:40 pbw mixture
of phenol and (1,1,2,2)-tetrachloroethane and a 50:50 pbw mixture of
trifluoroacetic acid and dichloromethane.

44. An industrial textile according to claim 32, constructed and arranged
to be used as at least one of an industrial filtration fabric and a
conveying fabric.

45. An industrial textile according to claim 32, constructed and arranged
to be used in a section of a papermaking machine selected from a forming
section, a press section and a dryer section, and the fabric is selected
from a forming fabric, a press fabric, a dryer fabric and a through air
dryer fabric.

46. An industrial textile according to claim 32, wherein the
thermoplastic polymer is a polyester having an intrinsic viscosity of at
least 0.7, determined using a mixture selected from a 60:40 pbw mixture
of phenol and (1,1,2,2)-tetrachloroethane and a 50:50 pbw mixture of
trifluoroacetic acid and dichloromethane

Description:

FIELD OF THE INVENTION

[0001] The present invention concerns oriented, thermoplastic polymer
elements, including yarns, fibers and films which offer increased
resistance to abrasion and provide a reduction in the frictional
characteristics in industrial textiles into which they are incorporated.
Specifically the invention concerns oriented thermoplastic polymer
elements into which dry lubricants such as particles of molybdenum
disulphide, boron nitride or tungsten disulphide have been incorporated
in amounts of from about 0.1% to about 10% by weight based on the total
weight of the elements, and woven or nonwoven fabrics made from or
incorporating the elements.

BACKGROUND OF THE INVENTION

[0002] Industrial textiles (also referred to as technical textiles) are
used in many consumer and industrial applications, either as a component
of the end product, or in the manufacture of one or more components.
These textiles are typically woven structures made from polymeric yarns
comprising a polyester, polypropylene, polyamide, polyethylene, glass
fibers or other similar materials; they may also be nonwoven structures
assembled from films, staple fibers, encapsulated yarn arrays and similar
components such as are known in the art. It is also known to assemble
industrial textiles from a plurality of helical coils, which are
intermeshed and interconnected in a hinged arrangement, by hinge or
pintle yarns. The component yarns, fibers or films from which the textile
is assembled may be monofilaments, multifilaments, spun yarns, cabled
yarns, homolayer or multilayer films and the like. One general class of
industrial textiles to which the present invention is particularly
relevant is filtration and conveying fabrics and, in particular,
papermaking fabrics.

[0003] However, although the present invention is discussed below with
particular reference to papermaking fabrics, it is applicable to any type
of industrial textile intended for conveying or filtration and which can
be constructed from polymeric elements, including, but not limited to,
textiles constructed by weaving, helical or spiral coil assembly,
pre-crimped yarn assembly, and selectively slit and embossed film, in
each case to provide a single layer textile, or one or more outer layers
in a multi-layer construction. In addition, as discussed further below,
the present invention is applicable to seaming elements for industrial
textiles, including such elements formed from films, or as spiral seaming
coils, or as seaming lumens.

[0004] In modern high speed papermaking processes, a highly aqueous stock
consisting of about 99% water and 1% papermaking solids is ejected at
high speed and precision onto an endless moving forming fabric. A nascent
web, which will be self coherent and consist of about 25% papermaking
solids by the end of the forming section, is formed as the stock is
drained through the fabric as it passes over various dewatering elements
and drainage boxes. This web is then transferred from the forming fabric
into the press section of the papermaking machine where, together with at
least one press felt, it passes through one or more nips where additional
fluid is removed by mechanical means. The web is then transferred into
the dryer section of the papermaking machine where it is supported on one
or more dryer fabrics as it passes in serpentine fashion over a series of
heated rotating drums where much of the remaining moisture is removed by
evaporative means. The finished sheet is then reeled into large rolls at
the end of the papermaking machine, and further finishing processes may
be applied. Tissue and towel forming processes are similar but employ a
so-called through-air dryer (TAD) fabric to convey the sheet through an
air drying section of the tissue-making machine where it is dried and
various physical properties are created in the final product.

[0005] Forming fabrics, press felts, dryer and TAD fabrics are critical to
the quality of the paper product that is ultimately produced on the
papermaking machine. In simplest terms, these fabrics are designed to
allow fluid from the stock to pass through the fabric in a controlled
manner, while providing uniform support to the papermaking solids. They
are also intended to provide consistent support for the paper web formed
and conveyed by them. Each of these fabrics is uniquely designed for
optimal performance in the environment for which it is intended. Forming
fabrics should be as thin as is possible, so as to minimize internal void
volume and water carrying capacity, while max support for the papermaking
fibers and other solids they convey. Press felts provide a void volume
into which water that is expressed from the web in a press nip may be
carried away so as to dry the sheet. Dryer fabrics are engineered to
carry and support the wet web while the remaining water is evaporated
from the sheet. Considerable efforts have been made by various
manufacturers of papermaking fabrics to provide textiles that are thin
yet sufficiently robust and dimensionally stable so as to survive the
environmental forces to which they are exposed. These fabrics are
routinely exposed to high temperatures and humidity, as well as abrasive
wear from their continuous sliding contact with the various stationary
components over which they travel at speeds in excess of 1,000 meters per
minute.

[0006] Industrial filtration and conveying fabrics, both woven and
nonwoven, are employed in various applications, including but not limited
to wastewater treatment, water supply, food processing, pharmaceutical
processing, chemical processing, and pigment and coating processes. Like
papermaking fabrics, these more generic industrial textiles are typically
made from thermoplastic polymer yarns or films whose properties are
selected and engineered in accordance with end use requirements.

[0007] In an effort to increase the performance characteristics of these
textiles, a wide variety of yarn and film materials have been employed in
their manufacture, including natural fibers, metals and, more recently,
yarns and films formed from thermoplastic polymers. The predominant
polymers in use today in the manufacture of papermaking and industrial
filtration fabrics include polyesters, in particular polyethylene
terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene
terephthalate (PTT), polyethylene naphthalate (PEN) and 1,4
cyclohexanedimethanol-terephthalate-co-isophthalate (PCTA), as well as
their various known blends and copolymers, and nylons, such as
polyamide-6 and polyamide-6/12, and various blends and formulations
thereof. Other non-limiting examples of thermoplastic polymers known and
used for such applications include blends of polyester and polyurethane
(Monalloy®), polyether ether ketone (PEEK), and polyphenylene
sulphide (PPS); others are known and used.

[0008] Papermaking fabrics, in particular forming and dryer fabrics, are
commonly woven using a thermoplastic polyester monofilament warp material
which is usually located in the machine direction (MD) of the final
fabric, and either polyester or polyamide monofilaments as the weft
material which are arranged in the cross-machine direction (CD), on the
machine side (MS) of the fabric where the majority of abrasive force is
applied transversely to the longitudinal dimension of the monofilament.
The preferred polyester for these applications is PET; however, it is
known to use PBT, PTT, PCTA and PEN, as well as copolymers and blends
containing PET and other polyesters. Polyamides are generally preferred
for use as at least a portion of the weft material in forming fabrics due
to their ability to resist abrasive wear in comparison to polyesters.
However, it is well known that the physical properties of polyamides, in
particular their hydrophilic nature and crimp behaviour during fabric
processing, introduce difficulties in both manufacturing (in particular
the weaving, heatsetting and seaming processes) and the end application,
where curl may occur in the outer edges of the forming fabric. These
difficulties occur due to the differing mechanical and thermal properties
of polyamides as compared to polyesters. It is also known that polyamides
are generally less inert than polyesters in acidic environments and will
deteriorate more quickly.

[0009] Polyester, in particular PET, is a stable polymer that moves
through fabric manufacturing processes from weaving to heatsetting and
seaming with relative ease due to its stable nature. End users of the
woven product seldom have difficulties with fabrics made from this
material as such fabrics tend to run without significant performance
issues (e.g. skewing, creasing, etc) and can loop through both the paper
forming stage and return/cleaning stages without notable difficulties.
However, on more demanding applications in the papermaking machine, where
the fabrics are exposed to higher than usual abrasive conditions,
polyester monofilaments can wear quickly when exposed to high vacuum
levels as they pass over multiple dewatering units. Previous attempts to
improve the MS wear resistance of these fabrics have focused on adding or
substituting monofilaments comprised of other polymers that offered
better abrasion resistance. Such efforts are described, for example, by
Bhatt et al. in U.S. Pat. No. 5,169,711 and U.S. Pat. No. 5,502,120, both
of which disclose blends of polyester and thermoplastic polyurethanes for
improved abrasion resistance over pure polyesters. Other similar efforts
are known. A known advantage of the polymer blend materials described by
Bhatt et al. in U.S. Pat. No. 5,169,711 and U.S. Pat. No. 5,502,120, in
comparison to polyamides, is their crimp behaviour during weaving and
heatsetting, as well as their proven ability to resist abrasive wear.
These polyester/polyurethane blends tend to act more like polyester,
which results in improved fabric processing.

[0010] At the seaming areas of industrial textiles, to minimize
discontinuity between those areas and the adjacent textile body, various
seaming elements are known and used which are constructed of polymers
either identical to, or closely compatible with, polymers from which the
textile body is constructed. Such seaming elements include, for example,
spiral seaming coils, and various constructions designed to engage the
respective textile edges and be connected together.

DISCUSSION OF PRIOR ART

[0011] Molybdenum disulphide has been utilized for many years as an
additive to polyamides so as to improve the abrasion resistance and lower
the overall coefficient of friction of the polyamide material and thereby
increase the wear life of components made from this polymer. Such use of
molybdenum disulphide as a component material for the manufacture of
polyamide monofilament is known. For example, U.S. Pat. No. 4,370,375
(Bond) discloses polyamide monofilaments containing molybdenum disulphide
and lithium bromide for use as transverse strands of woven forming
fabrics.

[0012] GB 2,315,499 (Draper) discloses microencapsulated photochromic dyes
incorporated into the polymer matrix of 10-20 denier staple fibers used
in a press felt batt. Either the textile yarns or a textile coating may
contain the photochromic material. Draper discloses that other additives
including molybdenum disulphide may be incorporated into the dye micro
capsules to enhance textile properties, e.g. to increase lubricity.

[0013] WO 00/55402 (Hinterkeuser) discloses a polyamide based monofilament
fiber that allegedly offers improved abrasion resistance properties in
comparison to pure polyamide by incorporation into the polyamide of an
effective amount of molybdenum sulphide in a manner similar to that
disclosed by U.S. Pat. No. 4,370,375 (Bond).

[0014] U.S. Pat. No. 5,585,430 (Patel et al.) discloses a pintle wire
formed by extrusion from e.g. nylon (polyamide 6, 6/6, 6/10, 6/12),
polyesters or copolyesters, PEEK, PPS, and no more than 3 wt % of a
schistose lubricant such as graphite, molybdenum sulphide, clays or a
silicate. The schistose material allegedly eases insertion of the pintle
wire into press and dryer fabrics because of reduced drag or friction,
and reduces wear between the pintle and seaming loops.

[0015] US 2009/0209695 (Yu et al.) discloses a thermoplastic composition
comprising a mixture of from 10 to 98 pbw of a polycarbonate polymer,
from 2 to 90 pbw of a polyester polymer, and from 0 to 5 pbw of a
polylactic acid polymer. It is stated in the disclosure (see pg. 7, para.
41) that one or more fillers can be added to the composition, including
molybdenum sulphide.

[0016] It is also known from U.S. Pat. No. 6,949,289 (Lawton et al.) to
use molybdenum disulphide as a coating; and known from US 2006/0110597
(Koralek) and U.S. Pat. No. 4,719,066 (Wells et al.), to add molybdenum
to polyesters and polyamides.

[0017] There is a well known need in the manufacture of industrial
textiles, particularly those intended for use in papermaking processes,
for polymer elements, including yarns, fibers and films, which offer
improvements in wear resistance over polyester, while simultaneously
reducing the frictional characteristic of these textiles in comparison to
similar fabrics formed from prior art materials, and which are further
free of the attendant processing difficulties associated with polyamides.
The present invention seeks to provide such polymeric elements, and
textiles formed therefrom.

[0018] It has now been found that it is possible to provide significant
improvements by both increasing the abrasion resistance and reducing the
frictional characteristics of industrial textiles, by providing extruded
and oriented thermoplastic polymer elements for a wide range of end use
applications, such polymeric elements being provided in suitable forms,
including as yarns, fibers or films, and containing an appropriate amount
of at least one dry lubricant selected from a group of suitable dry
lubricants.

SUMMARY OF THE INVENTION

[0019] In the following discussion, the term "yarn" refers to a continuous
strand. Yarns can include monofilaments formed from oriented
thermoplastic polymers as noted above, and which may or may not have a
sheath-core construction, and can also include polymeric multifilaments,
and cabled structures comprised of either or both monofilaments and
multifilaments. Such yarns can be provided for incorporation into woven
or nonwoven textile structures.

[0020] As used herein, the term "fibers" can include staple fibers (small
diameter fibers of varying lengths typically formed from nylons or
polyamides which may be consolidated such as by needling into a cohesive
mat typically used as a batt in press felts) and the like which are known
and used in the manufacture of industrial textiles.

[0021] As used herein, the term "film" refers to a thin, flexible sheet
comprised of one or more layers of a thermoplastic polymer which has been
uniaxially or biaxially oriented.

[0022] As used herein, the term "dry lubricant" refers to any material
which can be provided in dry particulate form for incorporation with the
selected thermoplastic polymer. For the purposes of the present
invention, dry lubricants include molybdenum disulphide, tungsten
disulphide, boron nitride, and soft metals including indium (In), lead
(Pb), tin (Sn), bismuth (Bi), cadmium (Cd) and silver (Ag).

[0023] As used herein, the expression "% pbw" refers to the percentage
parts by weight of the entire composition which is comprised of either
the dry lubricant or the thermoplastic polymer.

[0024] In relation to the particulate matter of the dry lubricants used in
the thermoplastic polymers of the invention, their dimensions are
expressed in relation to the average particle size, in microns (μ,
wherein 1μ=1×10-6 m); or nanometers (wherein 1
nanometer=1×10-9 m). In the thermoplastic polymeric elements
of the invention, the dry lubricant is typically provided as a very small
particle having an average particle size from about 0.05μ to about
100μ.

[0025] Molybdenum disulphide is an inorganic compound with chemical
formula MoS2. Its appearance and feel are similar to graphite and it
is used widely as a solid lubricant because of its low frictional
properties. It is known to "fill" other polymers, in particular
polyamides, with this material. Several non-limiting examples of polymers
to which molybdenum disulphide has been added include Nylatron® (trade
mark of DSM Plastics), Teflon® (trade mark of Du Pont for
polytetrafluoroethylene) and Vespel® (trade mark of Du Pont for a
polyimide based polymer). Others are known and used.

[0026] Tungsten disulphide is also an inorganic chemical compound, having
the molecular formula WS2. It occurs naturally as the rare mineral
called tungstenite and has a layered structure similar to that of
MoS2; it is one of the most lubricious substances known. Tungsten
disulphide was originally developed by NASA as a dry lubricant for
spacecraft components operating in a vacuum. It is known to use this
material in plastic mouldings, bearings, gearboxes, cutting and forming
tools, threaded and splined components to reduce fretting, galling and
seizing, and in various other applications where friction reduction is
important

[0027] Boron nitride is also an inorganic chemical compound, with formula
BN, consisting of equal numbers of boron (B) and nitrogen (N) atoms. BN
exists in both a crystalline, diamond-like form as well as a hexagonal
form similar to graphite; it is the hexagonal form which is commonly
used. Boron nitride is not found in nature and is produced from boric
acid or boron trioxide.

[0029] The present invention concerns oriented, thermoplastic polymeric
elements for use in industrial textiles, and into which an effective
amount of very small particulates, having an average particle size from
about 0.05μ to about 100μ, and comprised of a dry lubricant, has
been blended prior to extrusion. The dry lubricant is preferably selected
from at least one of molybdenum disulphide, tungsten disulphide, boron
nitride, or at least one soft metal such as indium (In), lead (Pb), tin
(Sn), bismuth (Bi), cadmium (Cd) and silver (Ag). The present invention
also concerns industrial textiles, particularly papermaking and
filtration fabrics, including these novel polymeric elements. The dry
lubricant may be incorporated into the polymer resin from which the
polymeric element is extruded by means of a masterbatch in quantities
sufficient to provide an amount of the dry lubricant between about 0.1%
parts by weight (pbw) up to about 10% pbw, based on the total weight of
the polymeric element. The masterbatch consists of a polymer, preferably
a polyester, which is enhanced with from about 15% - 20% pbw of the dry
lubricant, such as one of more of the materials listed above. The
masterbatch is incorporated into the polymer from which the fibers, yarn
or film are extruded in amounts sufficient to provide a final
concentration in the extrudate that is from about 0.1% pbw up to about
10% pbw. Alternatively, the dry lubricant can conveniently be added to
the extrudate using a gravity feed, or similar apparatus, located near
the extruder throat. Concentrations of the dry lubricant below about 0.1%
do not appear to provide marked improvements in the abrasion resistance
of the resultant fibers, yarn or film, while concentrations in excess of
about 10% may not provide further beneficial effects. Preferably, the
concentration of the dry lubricant in the extruded and oriented fibers,
yarn or film will be from about 0.5% to about 7% pbw. Most preferably,
the concentration of the dry lubricant in the extruded fibers, yarn or
film is between 1%-5% pbw.

[0030] Where a polyester is used to construct the polymeric element, this
can be selected from such as are commonly used in the manufacture of
monofilaments and the like and which are suitable for use in industrial
textiles such as papermaking fabrics. Preferably the polyester is
selected from the group consisting of polyethylene terephthalate (PET),
polybutylene terephthalate (PBT), polyethylene naphthalate (PEN) and the
like. Polyester alloys and polymer mixtures including a polyester, such
as a PET-TPU blend as described in U.S. Pat. No. 5,169,711 (Bhatt) and
other similar polyesters such as are commonly used in the manufacture of
industrial textiles for papermaking and like applications are suitable.

[0031] Preferably, the polyester into which the masterbatch is
incorporated will have an Intrinsic Viscosity (IV) of at least 0.55;
preferably the IV will be from about 0.60 to about 1.0. More preferably,
the IV of the polyester will be from about 0.80 to about 0.95 so as to
provide a final polymeric element with physical properties suitable for
use in papermakers and similar industrial textiles. For these types of
fabric applications, the IV of the polyester of the finished polymeric
element should be at least 0.7 or higher. Intrinsic Viscosity, where
identified herein, is measured on a solution of the polyester in a mixed
solvent comprising a 60:40 pbw mixture of phenol and
(1,1,2,2)-tetrachloroethane at 30° C. The IV can also be measured
using a 50:50 pbw mixture of trifluoroacetic acid and dichloromethane.

[0032] In general, the masterbatch polyester into which the dry lubricant
is incorporated will have an IV that is lower than the IV of the
polyester into which it is added. However, the IV of the masterbatch
polyester can be equal to or greater than that of the polyester into
which it is added. Extrusion requires addition of heat which will
normally lower the intrinsic viscosity of the polyester and degrade the
final properties of the resultant polymeric element.

[0033] The dry lubricant used in the present invention should be of a
substantially uniform particulate size and configuration. Preferably, the
dry lubricant has an average particle size of from about 0.05 to about
100μ. Preferably, the dry lubricant is uniformly dispersed within the
chosen polymer and in the final polymeric element.

[0034] The blending of the chemical constituents from which the yarns,
fibers and films of the present invention are extruded can be carried out
in any sequence suitable to the manufacturing operation. However, it has
been found convenient to dry blend the polymer material with the required
quantity of the masterbatch material to obtain the desired concentration
of dry lubricant in the final product and to ensure a reasonably uniform
dispersion of the dry lubricant. Alternatively the dry lubricant can
conveniently be added by a metered gravity feed in a known manner at the
extruder.

[0035] For monofilaments, after blending the chemical constituents, the
yarns are prepared according to customary techniques. The molten polymer,
together with the dry lubricant with which it is blended, as well as any
other additives (such as processing aids, colorants, and the like), is
extruded through a die into a quench medium, after which it is oriented.
The monofilaments can be extruded according to known methods using either
a single screw or a twin screw extruder; it is anticipated that twin
screw extrusion will provide more uniform blending of the dry lubricant
with the chosen polymer and hence is presently preferred. In general, the
diameter of circular cross-section monofilaments formed from the polymer
blend of the present invention will be from about 0.08 mm to about 1.2
mm, and is preferably from about 0.12 mm to about 0.5 mm. After
extrusion, the extruded polymeric material will undergo an orientation
step, involving a uniaxial or biaxial stretching and relaxation, as
appropriate and as known in the art of polymer extrusion, so as to align
the polymer chains of the extrudate, and thus enhance the physical
properties of the resulting material.

[0036] As noted above, the present invention is applicable to any type of
industrial textile intended for conveying or filtration and which can be
constructed from polymeric elements, including, but not limited to,
textiles constructed by weaving, helical or spiral coil assembly,
pre-crimped yarn assembly, and selectively slit and embossed film, in
each case to provide a single layer textile, or one or more outer layers
in a multi-layer construction. In addition, where it is sought to
minimize discontinuity at the seaming areas of such textiles by using
seaming elements which are constructed of polymers either identical to,
or closely compatible with, polymers from which the textile body is
constructed, the use of the polymeric elements of the present invention
for such seaming elements can be particularly advantageous in providing
improved physical properties, either for industrial textiles of the
present invention, or for industrial textiles not of the invention but
constructed of polymers with which the polymers of the seaming elements
can be selected to be compatible. Such seaming elements would include,
but not be limited to, spiral seaming coils, and various constructions
designed to engage the respective textile edges and be connected
together, in particular seaming lumens such as disclosed in WO
2010/121360 (Manninen), and elements formed from films such as disclosed
in PCT/CA2010/001955 (Manninen et al.).

[0037] The invention therefore seeks to provide an extruded and oriented
thermoplastic polymeric element for use in an industrial textile, wherein
the polymeric element is constructed of a material selected from yarn
material, fiber material and film, and comprises

[0038] (i) a thermoplastic polymer; and

[0039] (ii) at least one dry lubricant, selected from the group consisting
of molybdenum disulphide (MoS2), tungsten disulphide (WS2),
boron nitride (BN), and a soft metal, wherein the dry lubricant comprises
particulate matter having an average particle size in a range of between
about 0.05μ and about 100μ (5.0×10-8 m and about
1.0×10-4 m), and is present in the polymeric element in an
amount from between about 0.1% and about 10% parts by weight (pbw), based
on a total weight of the polymeric element.

[0040] The invention further seeks to provide an industrial textile
comprising at least one extruded and oriented thermoplastic polymeric
element, wherein each of the at least one polymeric element is
constructed of a material selected from yarn material, fiber material and
film, and comprises

[0041] (i) a thermoplastic polymer; and

[0042] (ii) at least one dry lubricant, selected from the group consisting
of molybdenum disulphide (MoS2), tungsten disulphide (WS2),
boron nitride (BN) and a soft metal, wherein the dry lubricant comprises
particulate matter having an average particle size in a range of between
about 0.05μ and about 100μ (5.0×10-8 m and about
1.0×10-4 m) and is present in the polymeric element in an
amount from between about 0.1% and about 10% parts by weight (pbw), based
on the total weight of the polymeric element.

[0045] (ii) at least one dry lubricant, selected from the group consisting
of molybdenum disulphide (MoS2), tungsten disulphide (WS2),
boron nitride (BN) and a soft metal, wherein the dry lubricant comprises
particulate matter having an average particle size in the range of
between about 0.05μ and about 100μ (5.0×10-8 m and about
1.0×10-4 m), and is present in the polymeric element in an
amount from between about 0.1% and about 10% parts by weight (pbw), based
on the total weight of the polymeric element.

[0048] (ii) at least one dry lubricant, selected from the group consisting
of molybdenum disulphide (MoS2), tungsten disulphide (WS2),
boron nitride (BN) and a soft metal, wherein the dry lubricant comprises
particulate matter having an average particle size in the range of
between about 0.05μ and about 100μ (5.0×10-8 m and about
1.0×10-4 m), and is present in the polymeric element in an
amount from between about 0.1% and about 10% parts by weight (pbw), based
on the total weight of the polymeric element.

[0050] Alternatively, the at least one dry lubricant is selected from the
group consisting of tungsten disulphide (WS2), boron nitride (BN),
and a soft metal, and the thermoplastic polymer comprises at least one
polyamide. Preferably such polyamide is selected from at least one of the
following:

[0059] Preferably, the dry lubricant comprises between about 0.5% and
about 7% pbw of the total weight of the polymeric element, and more
preferably between about 1% and about 5% pbw of the total weight of the
polymeric element.

[0060] Preferably, the average particle size of the particulate matter of
the dry lubricant is in a range of between about 0.1μ and 50μ
(1.0×10-7 m and about 5.0×10-5 m) ; more preferably
between about 0.5μ and about 20μ (5.0×10-7 m and about
2.0×10-5 m).

[0061] The polymeric element can be of any suitable form depending on the
intended end use, including a film comprising at least one layer; a fiber
material, which can comprise a staple fiber material; and a yarn material
having a construction selected from monofilament yarn, multifilament
yarn, spun yarn, cabled yarn and sheathed yarn.

[0062] In one embodiment, the polymeric elements of the invention can be
constructed from a yarn material or a film for use as seaming elements,
which can be used for seaming industrial textiles or many types, in
particular industrial textiles of the present invention.

[0063] The industrial textiles of the invention can comprise woven
structures including warp yarns and weft yarns, or nonwoven structures
including MD and CD yarns. Alternatively, they can comprise one or more
layers of film; or nonwoven structures wherein the at least one polymeric
element comprises a plurality of interconnected helically coiled yarns.
Additionally, the industrial textiles of the invention can comprise a
seaming element constructed as a polymeric element according to the
invention.

[0064] The industrial textiles of the invention can be constructed and
arranged to be used as industrial filtration fabrics or conveying
fabrics, and in particular to be used in a section of a papermaking
machine selected from a forming section, a press section and a dryer
section. For use in a papermaking machine, the fabrics can be forming
fabrics, press fabrics, dryer fabrics, particularly through air dryer
fabrics.

[0065] Where the polymeric element is a polyester, preferably the
polyester has an intrinsic viscosity of at least 0.7, determined using a
mixture selected from a 60:40 pbw mixture of phenol and
(1,1,2,2)-tetrachloroethane and a 50:50 pbw mixture of trifluoroacetic
acid and dichloromethane.

BRIEF DESCRIPTION OF THE DRAWINGS

[0066] The invention will now be described with reference to the drawings,
in which

[0067] FIG. 1 is a graph showing the results of dry friction testing of a
monofilament made in accordance with the teaching of the present
invention in comparison with three other monofilaments according to the
prior art;

[0068] FIG. 2 is a graph showing percent retained tensile loss under dry
test conditions of a monofilament prepared in accordance with the
teachings of the present invention in comparison to two other
monofilaments according to the prior art;

[0069] FIG. 3 is a graph showing the results of dry friction testing of
monofilaments prepared in accordance with the teachings of the invention
in comparison to one other monofilament according to the prior art; and

[0070] FIG. 4 is a graph providing comparative data for wet friction
testing of three monofilaments prepared in accordance with the teachings
of the invention in comparison to two other monofilaments.

DETAILED DESCRIPTION OF THE DRAWINGS

[0071] Referring first to FIG. 1, this is a graph demonstrating the amount
of force required to move a monofilament which is in contact with a solid
friction pin a measured distance according to the capstan friction test
method described in ASTM D 3108-95, entitled "Standard Test Method of
Coefficient of Friction, Yarn to Solid Material". The X-axis indicates
the distance as measured in inches, and the Y-axis indicates the force as
measured in pounds (lb.).

[0072] In FIG. 1, the results of testing four monofilaments, identified as
A, B, C and D, according to the test method are presented. Monofilament A
was a 0.40 mm diameter, circular cross-section, melt extruded and
oriented monofilament comprised of PET which further included 5% pbw
(parts by weight) of a dry lubricant, molybdenum disulphide, in particle
form uniformly distributed throughout the monofilament. The molybdenum
disulphide particles had an average particle size of about 6μ, and
were supplied by the manufacturer, Polyvel, Inc. of 100 Ninth Street,
Hammonton, N.J. 08037. Monofilament A was prepared in accordance with the
invention and had an Intrinsic Viscosity (IV) of about 0.75.

[0073] Comparison monofilaments B, C and D were also prepared in a manner
similar to that of monofilament A but did not contain any dry lubricant
dispersed in the polymer melt. Monofilament B did not contain a dry
lubricant, but was otherwise substantially similar to monofilament A, in
that it was a 0.40mm diameter circular cross-section monofilament, was
comprised of the same polyester (PET), and was produced to have an
Intrinsic Viscosity (IV) of about 0.75. Monofilament C contained a known
lubricant which was not a dry lubricant, but was otherwise also
substantially similar to monofilament A. Monofilament D was substantially
similar to monofilament B, but was produced so as to have a lower IV, of
less than 0.7. Following their preparation, the monofilaments A, B, C and
D were then tested so as to determine and compare the force required to
move them in a standard test similar to that described in ASTM D 3108-95,
the test being modified from that described in ASTM D 3108-95 only in
order to provide a constant and uniform tension to the monofilaments.

[0074] In the modified version of the ASTM D 3108-95 test used to obtain
the results shown in FIG. 1, the adjustable input tension applied to the
monofilaments prior to the friction pin was replaced with a 50 g mass
which was found to be appropriate for the size of the strands. In the
test, the 50 g mass was first suspended from one end of a yarn; the yarn
was then wrapped at a wrap angle of 450° about a capstan friction
pin. The opposite end of the yarn was then attached to a constant rate of
extension (CRE) type tensile testing machine provided with an appropriate
force gauge. The monofilament was then pulled a known distance and the
amount of force required to move that distance was measured (in pounds).
Each monofilament was exposed to the identical test conditions (applied
mass, wrap angle, friction pin) and the tests were repeated under the
same conditions a number of times, using the same materials, so as to
obtain a statistically significant result.

[0075] The results graphed in FIG. 1 show that the average force required
to pull the inventive monofilament A through the apparatus was, on
average, about 0.30 lb, whereas the force required to pull the prior art
monofilaments B, C and D through the same apparatus, under the identical
test conditions, was much higher and ranged from about 1.7 lb for
monofilaments B and C, to about 1.3 lb for monofilament D which had the
lowest IV of the monofilaments tested. The data presented in FIG. 1 thus
show that monofilaments prepared in accordance with the teachings of the
present invention require much less force to pull through a known
distance at a standard wrap angle around a common capstan friction pin,
and thus have a much lower coefficient of friction, than comparable
monofilaments which do not contain a proportion of the dry lubricant.

[0076] The coefficient of friction (μ) can be determined using the
formula:

μ = ln [ T afterwrap T beforewrap ] wrap angle
##EQU00001##

[0077] In the above formula, Tafter wrap is the average force
required to pull the monofilament (i.e. the Y-axis values in FIG. 1), and
Tbefore wrap is the 50 g mass which was suspended from the
monofilament before it wrapped the friction capstan at a wrap angle of
450°, which corresponds to 7.854 radians.

[0078] Referring next to FIG. 2, this is a graph showing the percentage
tensile loss under dry test conditions of monofilaments (A) prepared in
accordance with the teachings of the present invention, in comparison to
two similar monofilaments (E and F) of the prior art, which did not
include a dry lubricant.

[0079] In this test, the tensile strength of the various monofilament
samples is first determined using a suitable apparatus and test method.
For example, a CRE test apparatus, such as an Instron Tensile Testing
machine available from Instron Worldwide of Norwood, Mass. would be
appropriate; other tensile testing apparatus may also be satisfactory. A
standard procedure, such as that described in ASTM D2256 "Standard Test
Method for Tensile Properties of Yarns by the Single-Strand Method" may
be used. Any suitable test method can be selected, provided that each
sample is tested using the same procedure and test apparatus as all other
samples, so that the results obtained are directly comparable and provide
a reliable determination of the maximum tensile strength of the strand.

[0080] Following determination of the yarn tensile strength prior to
testing, a known length of each monofilament sample was fixedly attached
to one side of a so-called "squirrel cage" abrasion test apparatus. In
the test, the sample was draped over a rotatable, grooved ceramic wheel;
the opposite end of the sample was attached to a known mass so that the
sample rested in positive contact with the ceramic wheel. The ceramic
wheel was then rotated at constant speed under power with the
monofilament samples resting in contact with the wheel and the same
applied load attached to each, and the number of rotations (cycles)
recorded. The monofilament samples were removed from the test apparatus
at regular intervals of 100,000 cycles, and the tensile strength of each
sample was remeasured using the same test apparatus and method employed
to determine its original maximum tensile strength. The tensile strength
of each sample at each interval was compared to its original tensile
strength prior to abrasion under test, and the results were plotted as a
function of their loss in tensile strength (Tensile Loss (%)) in
comparison to the number of cycles to which the samples were exposed.

[0081] In the data presented graphically in FIG. 2, monofilament A was a
0.35 mm diameter, circular cross-section, melt extruded and oriented
monofilament of the invention, comprised of PET and including 1.7% pbw of
a dry lubricant, tungsten disulphide, in particle form uniformly
distributed throughout the monofilament. The tungsten disulphide was
purchased as dry particles from M.K. IMPEX Canada, 6382 Lisgar Drive,
Mississauga, Ontario L5N 6X1, Canada and the particle size as provided by
the supplier ranged from about 0.1 to 6.0 microns. To prepare the
monofilament A, the tungsten disulphide was uniformly dry blended with
the PET granules prior to monofilament extrusion; monofilament samples
were then extruded according to standard industry practices.

[0082] Monofilament E was a 0.35 mm diameter monofilament comprised of a
blend of about 60% PET and 40% thermoplastic polyurethane prepared in the
manner described in U.S. Pat. No. 5,502,120 (Bhatt et al.) and which did
not contain any dry lubricant. Monofilament F was a 0.35 mm diameter
polyamide monofilament such as would be used in the manufacture of
industrial textiles and which was prepared in accordance with the
teachings of U.S. Pat. No. 6,828,681. Monofilament F was comprised of a
blend of approximately 95% pbw polyamide 6/10 & 5% pbw polyamide 11 and
did not contain any dry lubricant.

[0083] As shown in the graph of FIG. 2, monofilament A, comprised of PET
and 1.7% pbw tungsten disulphide particles, lost less than 10% of its
original tensile strength following exposure to 600,000 rotation cycles
on the test apparatus. In comparison, monofilament E, comprised of the
blend of PET and thermoplastic polyurethane, lost about 30% of its
original tensile strength whilst the polyamide sample, monofilament F,
lost about 87% of its original tensile strength following exposure to
600,000 cycles.

[0084] The test data displayed graphically in FIG. 2 thus show that
polymeric monofilaments including about 1.7% pbw of a dry lubricant are
more resistant to abrasion, as determined by the percent tensile strength
remaining in them following exposure to prolonged dry abrasive effects,
than are comparable monofilaments that do not contain a dry lubricant, in
this case tungsten disulphide.

[0085] Referring now to FIG. 3, this is a graph showing the results of
friction testing of a monofilament sample (A) that was prepared in
accordance with the teachings of the invention, in comparison to a second
monofilament sample (B) which did not contain a dry lubricant. The test
was performed according to the methods described in relation to FIG. 1.
In this case, monofilament A was a 0.35 mm diameter circular
cross-section monofilament comprised of PET into which 1.7% pbw of
tungsten disulphide particles having a particle size ranging between 0.1
and 6 microns had been uniformly dry blended prior to extrusion.
Monofilament B did not contain any dry lubricant, but was otherwise
substantially identical to monofilament A, being also a 0.35 mm diameter
circular cross-section PET monofilament. The intrinsic viscosity of the
polyester of both monofilaments A and B was the same.

[0086] Both monofilaments were tested in accordance with the modified
version of test method ASTM D 3108-95 entitled "Standard Test Method of
Coefficient of Friction, Yarn to Solid Material" as described above. Both
monofilaments were tensioned at a wrap angle of 450° around the
friction capstan using the same 50 g weight and were pulled a distance of
about 9 inches; the force required to pull the monofilaments around the
friction capstan was measured using a CRE type tensile testing machine
provided with a suitable force gauge. Measurements of the force required
to pull the monofilaments around the capstan were taken continuously as
shown in the graph.

[0087] The data presented in FIG. 3 show that polyester monofilaments
including a dry lubricant according to the invention, specifically 1.7%
pbw tungsten disulphide particles whose sizes range between about 0.1 and
6 microns, require significantly less force to move through the measured
distance than comparable monofilaments that do not contain the dry
lubricant.

[0088] Referring now to FIG. 4, this is a graph demonstrating the amount
of force required to move a monofilament which is in contact with a solid
friction pin a measured distance according to the capstan friction test
method described in ASTM D 3108-95 entitled "Standard Test Method of
Coefficient of Friction, Yarn to Solid Material". The test was modified
in this instance from that described in ASTM D 3108-95 in that the yarns
and capstan friction pin were immersed in a water bath. The intent of
this test was to determine the force required to pull the monofilaments
the required distance when exposed to water and to further determine
whether any of the monofilaments behaved differently in such conditions
from the others.

[0089] In FIG. 4, the results of testing five monofilaments, identified as
G, H, I, J and K, in accordance with the modified wet friction test
method are presented. Other than with respect to the addition of a dry
lubricant into the polymer melt, all five monofilaments were
substantially similar, each being melt extruded from pelletized PPS
(polyphenylene sulphide) resin in a manner similar to that described
above in relation to the extrusion of PET; all the monofilaments were
extruded so as to provide a rectangular cross-section measuring 0.60 mm
in width by 0.30 mm in height. The composition of each monofilament with
respect to the dry lubricant additive was as follows:

[0090] Monofilament G: 2.0% pbw tungsten disulphide

[0091] Monofilament H: 1.1% pbw tungsten disulphide

[0092] Monofilament I: 1.0% pbw molybdenum disulphide

[0093] Monofilament J: 0.0% pbw dry lubricant

[0094] Monofilament K: 0.0% pbw dry lubricant +1% pbw colorant

[0095] In the monofilament samples of FIG. 4, samples G and H contained 2%
and 1.1% pbw respectively of tungsten disulphide. This material was
obtained as dry particles from M.K. IMPEX Canada, 6382 Lisgar Drive,
Mississauga, Ontario L5N 6X1, Canada and had a particle size as provided
by the supplier of between about 0.1 and 6.0 microns. The tungsten
disulphide was added in dry powder form to, and was compounded with, the
pelletized PPS. The PPS with which the dry lubricants were blended was
Fortron PPS which is a high-temperature linear PPS and was purchased from
Ticona Engineering Polymers, a business unit of Celanese Corporation of
Dallas, TX. The uniformly blended polymer resin pellets together with the
dry lubricant were then melt extruded and drawn as rectangular cross
sectional monofilaments.

[0096] Sample I was prepared in an identical manner to samples G and H
with the exception that 1% pbw of molybdenum disulphide dry lubricant was
used in place of the tungsten disulphide. The molybdenum disulphide had
an average particle size of about 6 microns. The molybdenum disulphide
was supplied by the manufacturer, Polyvel, Inc. of 100 Ninth Street,
Hammonton, N.J. 08037.

[0097] Monofilament J was produced identically to monofilaments G, H and I
but did not contain any dry lubricant additive; and monofilament K was
also produced similarly, without a dry lubricant, but 1% pbw of a
commercially available colorant was added to the polymer melt.

[0098] In the modified version of the ASTM D 3108-95 test used to obtain
the results shown in FIG. 4, the apparatus was modified to include a
water bath in which the capstan friction pin, and hence the yarns, were
immersed. The arrangement was otherwise essentially identical to that
described in relation to the test method used to obtain the data in FIG.
1. Each yarn was attached at one end to a 50g mass, and was attached at
the other to a CRE type tensile testing machine provided with an
appropriate force gauge. Each yarn was then wrapped at a wrap angle of
450° about the capstan friction pin, which was under water. The
monofilament was then pulled a known distance and the amount of force
required to move that distance was measured, in pounds. Each monofilament
was exposed to the identical test conditions (applied mass, wrap angle,
friction pin) and the tests were repeated under the same conditions a
number of times, using the same materials, so as to obtain a
statistically reliable and significant result.

[0099] The results graphed in FIG. 4 show that the average force required
to pull the inventive monofilaments G, H and I through the apparatus was,
on average, about 0.40 lb while the force required to pull the prior art
monofilament J, and the monofilament K which contained the colorant was
at least twice as great, at about 0.80 lb. The data presented in

[0100] FIG. 4 thus shows that monofilaments comprised of a blend of PPS
and dry lubricant, and prepared in accordance with the teachings of the
present invention, require much less force to pull through a known
distance at a standard wrap angle around a common capstan friction pin
while immersed in water, and thus have a much lower coefficient of
friction, than comparable monofilaments which do not contain a dry
lubricant.

[0101] The experimental information presented in FIGS. 1 to 4 thus shows
that monofilaments prepared in accordance with the teachings of the
present invention possess a lower coefficient of friction (as expressed
in terms of the amount of force required to move them a known distance
according to standard test methods), and exhibit a greater resistance to
abrasion (as measured by percent tensile loss following exposure to dry
abrasion conditions) in comparison to comparable monofilaments which do
not contain a dry lubricant such as molybdenum disulphide or tungsten
disulphide in amounts ranging from about 1.1% to 5% pbw. Alternatively,
as noted above, it is expected that many other dry lubricants will
provide similar results in monofilaments and films prepared in accordance
with the teachings of the present invention, for example boron nitride,
or a soft metal such as one or more of indium, lead, tin, bismuth,
cadmium or silver.

[0102] The yarns of the invention, constructed as monofilaments,
multifilaments or otherwise, can be woven or arranged into industrial
textiles, particularly papermaking fabrics, according to known and
conventional techniques. The fabrics may be woven using conventional
equipment, or they may be assembled from multiple yarn arrays according
to methods described elsewhere (see e.g., U.S. Pat. No. 6491794
(Davenport) and WO 05/056920 (Eagles)).The chosen weave construction or
yarn arrangement will depend on the intended end use application for
which the fabric is destined.

[0103] Where the polymeric elements of the present invention are provided
as yarns, such as monofilaments, they may be found particularly
satisfactory and effective when used in combination with other polymeric
yarn materials which do not contain dry lubricants. For example, the yarn
materials of the invention may be used in woven constructions where they
form the CD elements located on the MS of the fabric. In such a case,
they may comprise from as few as 25% to as much as 100% of the MS CD
yarns. The yarn materials of the invention may also be used as at least a
portion of the MD elements of the textiles, or as much as 100% of the MD
elements on the wear side of the textiles. As a further alternative, the
entire fabric may be assembled from monofilaments according to the
present invention.

[0104] After weaving or other fabric assembly processes, textiles
constructed of yarn materials are heatset according to conventional
techniques to stabilize the fabric structure. Heatsetting conditions will
vary with the chosen polymers, yarn materials, their size and the weave
construction, but will typically involve heating the fabric under tension
while it is mounted on a heatsetting frame such as is normally used for
this purpose.

[0105] Where the polymeric element is provided as a film, this can be as a
homolayer or one or more outer layers in a multilayer textile, as noted
above. In particular, the industrial textiles of the invention can
advantageously be provided as one or more layers of slit and profiled
films such as are described in PCT/CA2010/001956 (Manninen).

[0106] Further, as noted above, the polymeric elements of the present
invention can be used for various types of seaming elements for
industrial textiles, by incorporating the dry lubricant into the polymer
from which the seaming element, such as a spiral coil, seaming lumen or
film is constructed.

[0107] As discussed above, the dry lubricants act to improve the abrasion
resistance of the polymeric element while simultaneously lowering the
coefficient of friction of the resultant yarns and textiles made
therefrom. In addition to these benefits, the present invention also
provides the ability to take advantage of the physical properties of
polyester based materials over polyamide monofilaments of the prior art,
including moisture stability and dimensional stability, in that polyester
yarns do not expand or contract following wet-to-dry cycling in water and
air. The physical and chemical properties of the polymeric elements of
the present invention, other than the increased abrasion resistance and
reduced coefficient of friction as discussed herein, are substantially
similar to those already incorporated into known industrial textiles,
thus reducing or eliminating any issues of any need to modify fabric
design to accommodate the use of the polymeric elements of the invention.
In particular, it is now possible to manufacture fabrics entirely from
polyester based materials while reducing the overall coefficient of
friction of the fabric and improving its resistance to wear in comparison
to prior art fabrics which include a portion of polyamide based
materials.

Patent applications by ASTENJOHNSON, INC.

Patent applications in class SHEETS OR WEBS EDGE SPLICED OR JOINED

Patent applications in all subclasses SHEETS OR WEBS EDGE SPLICED OR JOINED